I have system with three camera. I have R and T matrix between C1 & C2 also between C2 & C3. How to transform a point from first camera to third camera?

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I have three cameras (C1, C2, C3). I have calibrated C1 & C2 as one stereo pair(System-1) and C2 & C3 (System-2) as another stereo pair. So in results, I have rotational and translation matrix between C1 & C2 also C2 & C3. After successful reconstruction, I have one 3D point say P(X, Y, Z) using system-1. So my question is how to transform Point P in all three cameras?